Method for preventing or treating influenza virus infection using pharmaceutical composition comprising immunoglobulin Fc-fused interleukin-7 fusion protein

ABSTRACT

The present invention relates to a pharmaceutical composition comprising an interleukin-7 fusion protein to which an immunoglobulin Fc region has been fused for preventing or treating diseases caused by influenza virus A. The fusion protein comprising the immunoglobulin Fc region and IL-7 according to the present invention protects the body from infection due to influenza virus A and thus can treat diseases which can be caused by the virus.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a National Stage of International Application No. PCT/KR2016/013966, filed on Nov. 30, 2016, which claims priority from U.S. Provisional Application No. 62/263,262, filed on Dec. 4, 2015.

TECHNICAL FIELD

The present invention relates to a composition of a fusion protein comprising interleukin-7 for preventing or treating viral infection, and more particularly, to a pharmaceutical composition which can be used for preventing or treating influenza virus infection comprising an interleukin-7 fusion protein in which immunoglobulin Fc region is fused.

BACKGROUND ART

Influenza A virus (IAV) is a seasonal epidemic virus which threatens human health. Recently, it has been reported that avian IAV variants including H5N1 and H7N9 can cross-infect humans with higher mortality than other strains of human-infecting IAV. In case of the avian IAV variants, no human-to-human transmission has been reported, but new IAV variants are likely to occur in humans without pre-existing immunity to the viral variant, which is a risk factor for the outbreak of global epidemic (Taubenberger J K et al., 2010, Public Health Rep 125 Suppl 3:16-26).

Although vaccinations against influenza virus are conducted every year, such vaccines have problems such as low productivity and low efficacy. In other words, it is very difficult to timely produce vaccines against new antigens found in mutant viruses.

Antiviral drugs such as a neuraminidase inhibitor, influenza virus therapeutic agent, have been reported to slow the progression of complications. In particular, it has been reported that treatment with a neuraminidase inhibitor within 2 to 3 days after IAV infection is effective in treating IAV (Dunning J et al., 2014, The Lancet infectious diseases 14:1259-1270). However, owing to the emergence of new viral variants resistant to antiviral drugs, one antiviral drug alone cannot prevent or treat all viral infections. Therefore, an effective countermeasure for highly pathogenic IAVs is urgently needed.

Accordingly, the present inventors have endeavored to develop a therapeutic agent capable of effectively inducing an immune response in vivo regardless of the mutation of the virus, and as a result, have found that an interleukin-7-Fc fusion protein has an excellent effect for the prevention and treatment of highly pathogenic influenza virus to complete the present invention.

DISCLOSURE OF INVENTION Technical Problem

An object of the present invention is to provide a composition for preventing or treating a disease caused by influenza virus.

Solution to Problem

In accordance with one object of the present invention, there is provided a pharmaceutical composition for preventing or treating a disease caused by influenza virus, comprising an interleukin-7 (IL-7) fusion protein in which immunoglobulin Fc region is fused.

In accordance with another object of the present invention, there is provided a method for preventing or treating a disease caused by influenza virus, comprising administering to an individual an interleukin-7 (IL-7) fusion protein in which immunoglobulin Fc region is fused and a pharmaceutically acceptable carrier.

Advantageous Effects of Invention

A fusion protein comprising immunoglobulin Fc region and IL-7 according to the present invention can control the immune system in the individual to protect human body from infection by influenza virus, and also, the fusion protein can control immune-related substances to treat a disease caused by the virus. Accordingly, it can be utilized as a new pharmaceutical composition which can replace the conventional antiviral vaccine.

BRIEF DESCRIPTION OF DRAWINGS

FIGS. 1a and 1b are graphs respectively showing weight change rate with respect to their initial body weight and survival rate of BALB/c mice depending on time passage after administration of IL-7-mFc through different routes.

FIGS. 2a and 2b are graphs respectively showing weight change rate with respect to their initial body weight and survival rate of BALB/c mice depending on time passage after intranasal administration of IL-7-mFc and IL-7, respectively, with various doses.

FIGS. 2c and 2d are graphs respectively showing weight change rate with respect to their initial body weight and survival rate of BALB/c mice depending on time passage after administration of 1 μg of IL-7-mFc and Fc-fragment, respectively.

FIGS. 3a and 3b are graphs respectively showing weight change rate with respect to their initial body weight and survival rate of C57BL/6 and FcRn^(−/−) mice depending on time passage after administration of PBS and 1 μg of IL-7-mFc, respectively.

FIGS. 4a and 4b are graphs respectively showing weight change rate with respect to their initial body weight and survival rate of BALB/c mice depending on time passage at day 0, 3, 5, 7, 14, 21 or 35 after intranasal administration of 1 μg of IL-7-mFc.

FIGS. 5a to 5f are graphs showing weight change rate with respect to their initial body weight and survival rate of BALB/c mice depending on time passage after infection with a lethal dose of A/PR/8/34 H1N1, A/California/04/09 H1N1 or A/Philippines/2/82 H3N2 at 14 days post-intranasal administration of IL-7-mFc.

FIG. 6 is a graph showing analysis of T_(RM)-like T cells not exposed to the anti-CD3 antibody present in the blood stream but reside in the local tissues, by an in vivo labeling experiment for analyzing the histological location of pulmonary-derived T cells increased by IL-7-mFc treatment.

FIGS. 7a and 7b are graphs showing that activated T cells specifically increase and no change of antibody response is observed in the IL-7-mFc pre-administration group after the IAV infection.

FIG. 8 is a graph showing the reduction of viral genes present in lung tissue of the IL-7-mFc pre-administration group after the IAV infection.

FIGS. 9a and 9b are graphs showing lung tissue lesions and the reducing effect of inflammatory cells in the IL-7-mFc pre-administration group after the IAV infection.

BEST MODE FOR CARRYING OUT THE INVENTION

In one aspect, the present invention provides a pharmaceutical composition for preventing or treating a disease caused by influenza virus, comprising an interleukin-7 (IL-7) fusion protein in which immunoglobulin Fc region is fused.

As used herein, the term “interleukin-7” may be a protein having the same amino acid sequence as interleukin-7 derived from an animal or a human. Further, the term “interleukin-7” may be a polypeptide or a protein having an activity similar to the interleukin-7 derived in vivo. Specifically, the IL-7 may be a protein comprising an IL-7 protein or a fragment thereof. Also, the IL-7 may be derived from a human, a rat, a mouse, a monkey, cattle or sheep.

The IL-7 comprises a polypeptide consisting of the amino acid sequences represented by SEQ ID NO: 1 to SEQ ID NO: 6. In addition, the IL-7 may have homology of about 70%, 75%, 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or more to the sequences of SEQ ID NO: 1 to SEQ ID NO: 6.

Specifically, human IL-7 may have an amino acid sequence represented by SEQ ID NO: 1 (Genbank Accession No. P13232); rat IL-7 may have an amino acid sequence represented by SEQ ID NO: 2 (Genbank Accession No. P56478); mouse IL-7 may have an amino acid sequence represented by SEQ ID NO: 3 (Genbank Accession No. P10168); monkey IL-7 may have an amino acid sequence represented by SEQ ID NO: 4 (Genbank Accession No. NP_001279008); bovine IL-7 may have an amino acid sequence represented by SEQ ID NO: 5 (Genbank Accession No. P26895); and sheep IL-7 may have an amino acid sequence represented by SEQ ID NO: 6 (Genbank Accession No. Q28540).

In addition, the IL-7 protein or a fragment thereof may comprise a variety of modified proteins or peptides, i.e., variants. Such modification may be carried out by substitution, deletion or addition of one or more proteins of wild-type IL-7, which does not alter the function of IL-7. These various proteins or peptides may have homology of 70%, 75%, 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% to a wild-type protein.

In general, substitution of a wild-type amino acid residue can be accomplished by substituting alanine or a conservative amino acid that does not affect the charge, polarity, or hydrophobicity of the entire protein.

The term “IL-7 protein” as used in the specification may be used as a concept including “IL-7 protein” and a fragment thereof. The terms “protein,” “polypeptide,” and “peptide” may be used interchangeably, unless otherwise specified.

In addition, the IL-7 may be a modified IL-7 having the following structure:

A-IL-7,

wherein said A is an oligopeptide consisting of 1 to 10 amino acid residues,

and the IL-7 is an interleukin-7 or a polypeptide having the activity similar to the interleukin-7.

Herein, said A may be directly linked to the N-terminus of the IL-7 or may be linked through a linker.

Said A may increase the productivity of IL-7 and may be prepared according to the method disclosed in Korean Patent Application No. 10-2016-0072769.

As used herein, said A may be linked to the N-terminus of IL-7. In the above formula, said A is characterized by containing 1 to 10 amino acids, which may be preferably selected from the group consisting of methionine, glycine, serine, and a combination thereof.

It is known that methionine and glycine do not induce an immune response in the human body. Although various protein therapeutic agents produced from E. coli necessarily contain methionine at the N-terminus thereof, no adverse immune effect has been reported. In the meantime, glycine is widely used in GS linker, and it is known that a commercial product such as Dulaglutide does not induce an immune response.

According to one embodiment, the oligopeptide A may be an oligopeptide comprising 1 to 10 amino acids selected from the group consisting of methionine (Met, M), glycine (Gly, G) and a combination thereof. Preferably, the oligopeptide A may be an oligopeptide consisting of 1 to 5 amino acids. For example, the oligopeptide A may be represented by the amino acid sequence selected from the group consisting of methionine, glycine, methionine-methionine, glycine-glycine, methionine-glycine, glycine-methionine, methionine-methionine-methionine, methionine-methionine-glycine, methionine-glycine-methionine, glycine-methionine-methionine, methionine-glycine-glycine, glycine-methionine-glycine, glycine-glycine-methionine, and glycine-glycine-glycine. Herein, the modified IL-7 may have any one of the amino acid sequences selected from SEQ ID NOS: 15 to 20.

Further, immunoglobulin Fc region may comprise an animal or human immunoglobulin Fc region, or a modified immunoglobulin Fc region thereof.

The IL-7 may be linked to the N-terminus or the C-terminus of the Fc region. It is known that even when IL-7 is fused to the C-terminus of the Fc region, IL-7 activity is maintained (U.S. Pat. No. 8,338,575 B2).

As used herein, the term “Fc region,” “Fc fragment” or “Fc” refers to a protein which comprises heavy chain constant region 2 (CH2) and heavy chain constant region 3 (CH3) of immunoglobulin but does not comprise variable regions of heavy or light chain and light chain constant region 1 (CL1). It may further comprise a hinge region of the heavy chain constant region. Hybrid Fc or a hybrid Fc fragment may herein also be referred to as “hFc” or “hyFc.” Also, as used herein, the term “a modified immunoglobulin Fc region” or “Fc region variant” refers to the Fc region in which one or more amino acids in the Fc region are substituted or the Fc region which is prepared by combining different Fc regions. Preferably, it refers to a Fc region whose binding force with a Fc receptor and/or a complement has been modified so as to exhibit weakened antibody-dependent cell-mediated cytotoxicity (ADCC) or complement dependent cytotoxicity (CDC) compared to the wild-type Fc region. The modified immunoglobulin Fc region can be selected from the group consisting of IgG1, IgG2, IgG3, IgD, IgG4, and a combination thereof.

In particular, the modified immunoglobulin Fc region comprises CH2 domain and CH3 domain in the N-terminus to C-terminus direction, wherein the CH2 domain comprises a portion of an amino acid residue of CH2 domain of human IgD and human IgG4, and the CH3 domain comprises a portion of an amino acid residue of human IgG4 CH3 domain.

The Fc region variant can be modified so as to increase the stability of the hinge region. Specifically, the 144^(th) amino acid and/or the 145^(th) amino acid of SEQ ID NO: 9 can be modified. Preferably, the variant may be a mutant in which K, the 144^(th) amino acid of SEQ ID NO: 9, is substituted by G or S, and E, the 145^(th) amino acid, is substituted by G or S.

In addition, the hFc can be represented by the following formula (I): N′-(Z1)p-(Y)q-Z2-Z3-Z4-C′,  [Formula (I)]

wherein,

N′ is the N-terminus of a polypeptide and C′ is the C-terminus of the polypeptide,

p or q is an integer of 0 or 1,

Z1 is an amino acid sequence having 5 to 9 consecutive amino acid residues in the N-terminus direction from the 98^(th) position in the amino acid residues at 90^(th) to 98^(th) positions of SEQ ID NO: 7,

Y is an amino acid sequence having 5 to 64 consecutive amino acid residues in the N-terminus direction from the 162^(th) position in the amino acid residues at 99^(th) to 162^(nd) positions of SEQ ID NO: 7,

Z2 is an amino acid sequence having 4 to 37 consecutive amino acid residues in the C-terminus direction from the 163^(rd) position in the amino acid residue at positions 163^(rd) to 199^(th) in SEQ ID NO: 7,

Z3 is an amino acid sequence having 71 to 106 consecutive amino acid residues in the N-terminus direction from the 220^(th) position in the amino acid residues at 115^(th) to 220^(th) positions of SEQ ID NO: 8, and

Z4 is an amino acid sequence having 80 to 107 amino acid residues in the C-terminus direction from the 221^(st) position in the amino acid residues at 221^(st) to 327^(th) positions of SEQ ID NO: 8.

In addition, Fc fragment of the present invention may be a wild type sugar chain, an increased sugar chain compared with the wild type, a reduced sugar chain compared with the wild type, or a form in which the sugar chain is removed. The increase, reduction or removal of immunoglobulin Fc sugar chain can be carried out by a conventional method known in the art such as chemical method, enzymatic method and genetic engineering method using microorganisms. The removal of the sugar chain from Fc fragment rapidly reduces the binding affinity of the primary complement component C1 to C1q and results in a decrease or loss of ADCC (antibody-dependent cell-mediated cytotoxicity) or CDC (complement-dependent cytotoxicity), thereby not inducing unnecessary immune responses in vivo. In this regard, immunoglobulin Fc fragment in a deglycosylated or aglycosylated form may be more suitable for the purpose of the present invention as a carrier of a drug. As used herein, the term “deglycosylation” refers to enzymatical elimination of sugar from Fc fragment, and the term “aglycosylation” refers to the production of Fc fragment in an unglycosylated form by a prokaryote, preferably E. coli.

The modified immunoglobulin Fc region may comprise amino acid sequences of SEQ ID NO: 9 (hFc01), SEQ ID NO: 10 (hFc02), SEQ ID NO: 11 (hFc03), SEQ ID NO: 12 (hFc04) or SEQ ID NO: 13 (hFc05). In addition, the modified immunoglobulin Fc region may comprise the non-lytic mouse Fc of SEQ ID NO: 14.

According to the present invention, the modified immunoglobulin Fc region may be one described in U.S. Pat. No. 7,867,491, and the production of the modified immunoglobulin Fc region may be carried out with reference to the disclosure of U.S. Pat. No. 7,867,491.

In addition, the interleukin-7 fusion protein in which immunoglobulin Fc region is fused may have the amino acid sequence of any one of SEQ ID NOS: 21 to 27.

Meanwhile, the influenza virus may be Influenza A virus (IAV). In addition, the influenza A virus may have various kinds of H types and N types. The virus may specifically be one of 16 kinds of H subtypes and may be one of 9 kinds of N subtypes. For a specific example, the virus may be, but not limited to, H7N9, H5N1, H5N2, H3N2 or H1N1.

The interleukin-7 fusion protein in which immunoglobulin Fc region is fused according to the present invention may further comprise a pharmaceutically acceptable carrier. The pharmaceutically acceptable carrier may be any carrier that is suitable for being delivered to a patient and is non-toxic to the patient. Distilled water, alcohol, fats, waxes and inert solids may be included as carriers. Pharmacologically acceptable adjuvant (a buffer or a dispersant) may also be included in the pharmacological composition.

In another aspect of the present invention, there is provided a method for preventing or treating a disease caused by influenza virus, comprising administering to an individual an interleukin-7 (IL-7) fusion protein in which immunoglobulin Fc region is fused and a pharmaceutically acceptable carrier.

Herein, the method of administration to an individual may be a local administration, preferably intranasal administration. In case of that the composition of the present invention is provided topically, such as intranasal or aerosol administration, the composition preferably comprises a portion of an aqueous or physiologically compatible body fluid suspension or solution. Accordingly, the carrier or vehicle may be physiologically acceptable, and thus it can be added to the composition and delivered to the patient, which does not adversely affect the electrolyte and/or volume balance of the patient. Thus, a carrier for a formulation may generally include physiologic saline.

The method for preventing or treating a disease using a fusion protein of the present invention or a composition comprising the same may comprise administering another drug or physiologically active substance having the effect of preventing or treating a disease in combination with the protein or the composition of the present invention, while the route, timing, and dosage of the co-administration may be determined depending on the type of a disease, disease condition of a patient, the purpose of treatment or prevention, and other drug or physiologically active substance co-administered.

The isolated nucleic acid molecule encoding the modified interleukin-7 or a fusion protein comprising the same may encode a polypeptide having an amino acid sequence selected from the group consisting of SEQ ID NOS: 15 to 25. The nucleic acid molecule may comprise a polynucleotide sequence selected from the group consisting of SEQ ID NOS: 29 to 39. The nucleic acid molecule may further comprise a signal sequence or a leader sequence.

MODE FOR THE INVENTION

Hereinafter, the present invention will be described in more detail with reference to the following examples. However, the following examples are for illustrative purposes only and are not intended to limit the scope of the present invention.

Preparation Example 1: Preparation of Experimental Animals

BALB/c, BALB/c-nude, C57BL/6, and FcRn^(−/−) mice used in the following examples were purchased from the Jackson Laboratory (Bar Harbor, Me., USA) and raised under specific pathogen-free conditions in an approved animal facility at POSTECH Biotech Center and International Vaccine institute (Seoul, Korea). All mouse experiments were performed in accordance with National Institutes of Health guidelines, and protocols were approved by the Institutional Animal Care and Use Committee (IACUC).

Preparation Example 2: Preparation of Mice and Antibody Administration Method

The murine non-lytic Fc fused IL-7 and non-lytic Fc fragment were prepared (Kim E S et al., 2013, Nanoscale 5:4262-4269). Recombinant human IL-7 (IL-7) used in the following examples was purchased from Shenandoah Biotechnology (Warwick, Pa., USA). A mixture of ketamine (100 mg/kg; Yuhan, Korea) and xylazine hydrochloride (10 mg/kg; Bayer, Belgium) in PBS was administered to the mice intraperitoneally to anesthetize, and then, 50 μl of PBS including predetermined cytokine was administered to the mice via indicated routes with a micropipette or syringe. The depletion monoclonal antibodies (mAbs) against mouse CD4 (GK1.5), CD8 (2.43), Vγ2 (UC3-10A6), and polyclonal rat IgG were purchased from Bioxcell (West Lebanon, N.H., USA). 200 μg of each depletion mAb was administered to the mice intraperitoneally at −1, 0, 1, and 4 days of post-IAV infection.

Preparation Example 3: Virus Infection and Titration

Influenza strains H1N1 (A/Puertorico/8/34) and H5N2 (A/aquatic bird/ma81/2007) used in the following examples were kindly provided by Young Ki Choi from Chungbuk National University of Medicine (Korea). Mice adapted to H5N2 were generated by passaging the H5N2 (A/Aquatic bird/Korea/W81/05) (Song M S et al., 2009, Journal of virology 83:12325-12335). At the predetermined time point after IL-7-mFc treatment, mice were anesthetized and infected intranasally with 3 LD₅₀ of PR8 or H5N2. Experiments using H1N1 (A/California/04/09) and H3N2 (A/Philippines/2/82) were performed with the aid of International Vaccine Institute (Korea). Body weight change and survival were monitored daily and groups with more than 50% of dead mice were excluded from the body weight graph. Mice that lose weight more than 30% with respect to their initial body weight were euthanized.

To measure virus titers, total lung homogenate samples of 3 and 7 days after infection, which were diluted 4 times with ten-fold serial dilution, were added to a monolayer of Madin-Darby canine kidney (MDCK) cells and the cytopathic effects were monitored daily. Virus titer was determined by a hemagglutinin test and calculated by the Reed and Muench method (Kim E H et al., 2013, Virology journal 10:104). Virus titer was described as log₁₀ of the 50% tissue culture infective dose (TCID₅₀)/ml.

Preparation Example 4: BALF Collection and Lung Homogenate Preparation

The mice were anesthetized, and bronchoalveolar lavage fluid (BALF) was collected with 1 ml of PBS. After BALF collection, the lungs were collected and minced into small pieces and treated with type I collagenase (Gibco/Life Technology, Grand Island, N.Y., USA) and DNase I (Sigma-Aldrich, St. Louis, Mo., USA) at 37° C. for 30 to 45 min. Tissue fragments were harvested and crushed through a 70-μm strainer (BD Biosciences/Falcon™, San Jose, Calif., USA) to generate single cell suspensions. The cells were then washed and resuspended with RPMI-1640 (Welgene, Korea) containing 10% FBS (Hyclone, South Logan, Utah, USA), 2-mercaptoethanol (Gibco), and antibiotics (Gibco).

Preparation Example 5: Quantification of Cytokines, Chemokines, Influenza-Specific Antibodies and Total Proteins in the BALF and Sera

The levels of cytokines and chemokines were first identified with a milliplex MAP mouse cytokine/chemokine kit (Millipore, Billerica, Mass., USA), and further analyzed using ELISA DuoSet kits (R&D systems, Minneapolis, Minn., USA) for mouse IFN-

, IL-6, G-CSF, MCP-1, and IP-10 according to the manufacturer's protocol. Total protein concentrations in the BALF were measured using protein assay dye reagent (Bio-Rad, Hercules, Calif., USA) based on BSA (Roche, Germany) as a standard. To quantify the level of influenza-specific antibodies, total IgG and IgA were analyzed by direct ELISA with inactivated H5N2 virus. Total IgG-HRP and IgA-HRP were purchased from Southern Biotech (Birmingham, Ala., USA).

Preparation Example 6: Flow Cytometry

To prevent non-specific antibody binding, the single-cell suspensions of lung homogenate were incubated with Fc-blocker (2.4G2; eBioscience, San Diego, Calif., USA) in staining buffer (1% FBS in PBS). The cells were then stained with the following mAbs; mAbs against B220, CD3, CD4, CD8, CD11a, CD11b, CD11c, CD44, CD49d, CD62L, CD69, DX5, F4/80, Ly6C, MHC II, IFN-γ, TCRγδ, and 7-AAD (all from eBioscience); and mAbs against CD19, CD45, Gr-1, and Ly6G (all from BD Biosciences). For the intracellular cytokine staining of IFN-γ-producing CD8 T cells, lung homogenates were incubated for 6 hours with HA peptide (residue 529-543, Peptron, Korea), Brefeldin A (eBioscience) and DNase I (Sigma), and then stained using Cytofix/cytoperm in accordance with the manufacturer's protocol (BD Bioscience). All samples were analyzed with LSR Fortessa (BD Biosciences) and FlowJo software (Tree Star, St, Ashland, Oreg., USA).

Preparation Example 7: In Vivo Antibody Labeling

The mice were treated with PBS or 1 μg of IL-7-mFc intranasally. To analyze the pulmonary residency of T cells, at 7 and 14 days after IL-7-mFc treatment, 2.5 μg of anti-mouse CD3e-percp-cy5.5 (BD bioscience) was intravenously administered to the mice at 10 min prior to sacrifice (Anderson K G et al., 2014, Nature protocols 9:209-222). Residual antibody was removed by cardiac perfusion with PBS, and the lung resident T cell populations in single cell suspensions of lung homogenate were analyzed by flow cytometry.

Preparation Example 8: Histological Analysis and Inflammation Score Measurement

Mice were anesthetized, and the lungs were obtained via thoracotomy and transcardial perfusion with cold PBS. Perfused lungs were immediately fixed with 4% paraformaldehyde, kept at 4° C. overnight, and embedded into paraffin. Lung sections were then stained with hematoxylin and eosin solution (H&E, Sigma Aldrich). The images of whole lung tissues were captured with a Pannoramic MIDI slide scanner (3DHISTECH, Hungary). Pulmonary inflammation was assessed by the degree of peribronchiolar and perivascular inflammation (Choi J P et al., 2010, Allergy 65:1322-1330).

Preparation Example 9: mRNA Preparation, cDNA Synthesis, and Quantitative PCR Analysis of Lung Homogenate

After preparation of lung homogenate, mRNAs were prepared with a Reliaprep™ mRNA preparation kit (Promega, Fitchburg, Wis., USA), and cDNAs were synthesized with GoScript™ Reverse Transcriptase System (Promega) according to the manufacturer's protocol. Quantitative PCR assay was performed using Power SYBR Green Master Mix (Applied Biosystems, Foster City, Calif.). The following primers for qPCR analysis were synthesized by Genotech (Korea): NS-1 forward, TGCGGGAAAGCAGATAGTGG (SEQ ID NO: 41); NS-1 reverse, TCAGTTAGGTAGCGCGAAGC (SEQ ID NO: 42); L32 forward, GAAACTGGCGGAAACCCA (SEQ ID NO: 43); L32 reverse, and GGATCTGGCCCTTGAACCTT (SEQ ID NO: 44). Relative expression levels of H5N2 NS-1 mRNA were normalized to the level of L32 mRNA.

Preparation Example 10: Statistical Analysis Method

A two-tailed Student's t-test (*, p<0.05; **, p<0.01) was used to evaluate the differences between two groups. A one-way ANOVA with Bonferroni's post-test (**, p<0.01) was used for more than three groups. Differences in survival rates between groups were determined by a log-rank test (†, p<0.05; ††, p<0.01).

Example 1: Confirmation of Protective Effect of IL-7 Against IAV Infection and Pathway Dependence

BALB/c mice (n=8/group) were treated with 1 μg of IL-7-mFc via various routes such as intranasal (i.n.), intramuscular (i.m.), intraperitoneal (i.p.) and subcutaneous (s.c.) routes, and then infected with 3 LD₅₀ of mouse adaptive avian influenza (H5N2, A/Aquatic bird/Korea/ma81/2005) after 2 weeks of IL-7-mFc treatment. The results are shown in FIGS. 1a and 1 b.

As shown in FIGS. 1a and 1b , intranasal IL-7-mFc treatment completely protected mice against lethal influenza infection, whereas IL-7-mFc treatment via an intramuscular, intraperitoneal and subcutaneous route showed no significant protection. These results reveal that induction of local immune responses by IL-7-mFc at the pathogen entry site, namely, the airway mucosa, may be critical for the protection against lethal IAV infection.

Example 2: Confirmation of Effective Dosage of IL-7-mFc Against IAV Infection and Function of Fc Fusion of IL-7

BALB/c mice (n=6/group) were treated with various ranges of doses among 0.04 μg to 10 μg of IL-7-mFc and 1 μg to 10 μg of recombinant human IL-7 (rhIL-7), and after 14 days, the mice were infected with 3 LD₅₀ of H5N2.

As a result, as shown in FIGS. 2a and 2b , no protection against IAV infection was observed in the mice treated with 0.04 μg of IL-7-mFc. In the mice treated with 0.2 μg of IL-7-mFc, 50% survival rate and partial protection against IAV were observed. In the mice treated with 1 μg, 3 μg, and 10 μg, i.e., 1 μg or more of IL-7-mFc dose, 100% survival rate and complete protection against IAV were observed. On the other hand, no protection against IAV was observed when 1 μg or more of rhlL-7 without Fc fusion was administered (1 μg, 3 μg and 10 μg).

In addition, BALB/c mice (n=6-8/group) were respectively treated with 1 μg of IL-7-mFc and 1 μg of Fc fragment (for comparison), at 14 days before IAV infection. After infection with 3 LD₅₀ of H5N2, the weight change with respect to the initial body weight and survival rate of the mice were observed for 20 days.

As a result, as shown in FIGS. 2c and 2 d, 100% survival rate was observed in the mice treated with 1 μg of IL-7-mFc, whereas no protection was observed in the mice treated with 1 μg of Fc fragment.

These results confirm that the effective dose of IL-7-mFc for complete protection from IAV infection in mice is 1 μg or more. It was also found that Fc fragment alone did not have protection function against IAV infection.

Example 3: Confirmation of the Relationship Between FcRn and the Protective Effect Against IAV Infection

PBS and 1 g of IL-7-mFc, were intranasally administered to C57BL/6 and FcRn^(−/−) (neonatal Fc receptor-deficient) mice (n=8/group), and after 14 days, mice were infected with 3 LD₅₀ of H5N2 viruses.

As a result, as shown in FIGS. 3a and 3b , none of the PBS-administered C57BL/6 and FcRn^(−/−) mice showed any protection against IAV infection. Among the IL-7-mFc-treated mice, C57BL/6 mice showed protection against infection, whereas no protection against IAV infection was observed in FcRn^(−/−) mice.

These results indicate that the protective immune response of the IL-7-Fc fusion protein arised from FcRn-dependent mechanism (transcytosis).

Example 4: Confirmation of Long-Term Protection Effect of IL-7-Fc Fusion Protein Against Lethal IAV Infections

BALB/c mice (n=11/group) were infected with 3 LD₅₀ of H5N2 at 0, 3, 7, 14, 21 or 35 days after intranasal administration of 1 μg of IL-7-mFc.

As a result, as shown in FIGS. 4a and 4b , the protective effect of IL-7-mFc was observed at 5 days after IL-7-mFc treatment, but no protective effect was observed at days 0 to 3. Complete protection against IAV was observed at 7 days and even at 14 days after IL-7-mFc treatment. This protective effect diminished over time but 63% and 36% of mice survival rate were found at 21 days and 35 days after IL-7-mFc treatment, respectively.

These results indicate that the protective effect of IL-7-mFc against IAV infection persists from 5 to 35 days after IL-7-mFc treatment.

Example 5: Confirmation of the Protective Effect of the IL-7-Fc Fusion Protein Against the Variant Virus

BALB/c mice (n=6/group) were infected with lethal doses of IAV varians of H1N1 (A/Puerto Rico/8/34 and A/California/04/09) and H3N2 (A/Philippines/2/82) at 14 days after IL-7-mFc nasal administration. The mean weight loss was shown as the percentage relative to the initial weight at the time of infection (mean±SEM) and the survival rate was analyzed by the Kaplan-Meier method. The protective effects of IL-7-mFc against infection of H1N1 (A/Puerto Rico/8/34), H1N1 (A/California/04/09) and H3N2 (A/Philippines/2/82) are shown in FIGS. 5a to 5 f.

As shown in FIGS. 5a to 5f , all mice pretreated with IL-7-mFc at 14 days before infection with H1N1 (A/Puerto Rico/8/34), H1N1 (A/California/04/09) and H3N2 (A/Philippines/2/82) showed protective effect.

These results indicate that IL-7-Fc fusion protein effectively induces local immune response regardless of the mutation of the virus, thereby improving the survival rate.

Example 6: Evaluation of Effect of IL-7-Fc Fusion Protein on Pulmonary T Cells

The numbers of lymphocytes in the lung tissues were analyzed at 0, 3, 7, 14, 21, and 35 days after intranasal administration of 1 μg of IL-7-mFc to the mice. At each point, the absolute numbers of immune cells in the total lung homogenate were calculated based on the percentage of the total cells by flow cytometry. The results shown in Table 1 were expressed as the mean±SEM of four mice/group (N.D., not determined; *, p<0.05; **, p<0.01 by Student's t test compared with cell numbers on day 0 (Table 1)). The expression of CD11a and CD49d in lung CD4 and CD8 T cells of BALBb/c (n=4) mice with CD62L^(high)CD44^(low) and CD62L^(low)CD44^(high) phenotypes to which IL-7-mFc had been administered was analyzed by flow cytometry.

TABLE 1 Absolute cell numbers after IL-7-mFc treatment Day 0 Day 3 Day 7 Day 14 Day 21 Day 35 Total CD4 0.68 ± 0.07 0.76 ± 0.03 2.08 ± 0.28** 0.89 ± 0.19 0.79 ± 0.14 0.70 ± 0.07 T cells (×10⁶) CD62L^(low)CD44^(high) CD4 0.58 ± 0.08  1.44 ± 0.08** 7.80 ± 1.24**  1.61 ± 0.25**  0.93 ± 0.05** 0.69 ± 0.05 T cells (×10⁵) Total CD8 0.31 ± 0.07 0.32 ± 0.01 0.75 ± 0.11** 0.42 ± 0.08 0.36 ± 0.08 0.28 ± 0.03 T cells (×10⁶) CD62L^(low)CD44^(high) CD8 0.18 ± 0.03  0.29 ± 0.02* 1.22 ± 0.14**  0.50 ± 0.12* 0.25 ± 0.03 0.26 ± 0.04 T cells (×10⁵) γδ 0.24 ± 0.02  0.39 ± 0.01** 4.71 ± 0.59**  0.54 ± 0.16**  0.40 ± 0.06*  0.38 ± 0.02** T cells (×10⁵) B cells (×10⁶) 0.84 ± 0.17 0.97 ± 0.03 2.27 ± 0.38*  1.13 ± 0.10 0.83 ± 0.18 N.D. NK cells (×10⁶) 0.36 ± 0.03  0.58 ± 0.03* 0.71 ± 0.07** 0.39 ± 0.04 0.29 ± 0.05 N.D.

As shown in Table 1, IL-7-mFc significantly and temporarily increased the number of various immune cells including CD127 (receptor of IL-7)-expressing immune cells including CD4, CD8, γδ T cells and B cells.

Example 7: In Vivo Antibody Labelling Experiment to Confirm that Pulmonary T Cells are Lung-Retentive

BALB/c mice were sacrificed at 7 days after intranasal administration of PBS and IL-7-mFc. 10 minutes prior to sacrifice, 2.5 μg of CD3 mAb-conjugated Percp-Cy5.5 was administered intravenously to the mice. The remaining antibodies in the blood stream were removed by perfusion and a single cell suspension was prepared. T cells in the bloodstream (circulating T cell) are labeled by antibodies, but T cells in lung tissue (lung-retentive T cells) are not labeled by antibodies. At 7 and 14 days after IL-7-mFc treatment, the numbers of cells labeled (in vivo CD3⁺ in vitro CD3⁺) or those not labeled (in vivo CD3⁻ in vitro CD3⁺) by in vivo CD3 label were analyzed. Through such method, it can be determined that the cells not labeled by in vivo CD3 label are lung retentive cells, and the cells labeled by in vivo CD3 label are those mainly in the bloodstream.

As shown in FIG. 6, the number of ‘labeled’ T cells returned to basal levels while the number of ‘unlabelled’ T cells was still significantly increased even at 14 days after treatment.

Example 8: Effect of Intranasal IL-7-Fc Fusion Protein Pretreatment on the Pulmonary T Cells and H5N2-Specific IgG Titer in the BALF after IAV Infection

BALB/c mice were treated with IL-7-mFc intranasally and infected with 3 LD₅₀ of H5N2 after 14 days. Absolute numbers of T cells from total lung homogenate were measured at days 3 and 7 after infection. Frequency of CD62L^(low)CD44^(high) population of CD8 and CD4 T cells were analyzed at day 7 after infection. Absolute number of pulmonary B and NK cells were measured at days 3 and 7 after infection. H5N2-specific IgG titer was analyzed in the BALF and sera at day 7 after infection. The results are shown in FIGS. 7a and 7 b.

As shown in FIGS. 7a and 7b , the number of pulmonary T cells containing CD8, CD4 and γδ T cells was increased by IL-7-mFc pretreatment after IAV infection compared with PBS treatment, and IAV-specific IgG production in BALF and serum was not further up-regulated.

These results indicate that the IL-7-Fc fusion protein induces a protective effect against fatal IAV infection by significantly increasing T cells directly involved in the immune response rather than the antibody response.

Example 9: Confirmation of the Relationship Between IL-7-Primed T Cells and Virus Removal

The viral titer and relative expression of H5N2 NS-1 mRNA (normalized by housekeeping-gene L32) in total lung homogenate were analyzed at day 3 and 7 after infection. The results are shown in FIG. 8.

As shown in FIG. 8, the expression level of H5N2 NS-1 mRNA was greatly reduced in the total lung homogenate of IL-7-mFc-treated mice.

Example 10: Effect of IL-7-Fc Fusion Protein on Pulmonary Pathology Induced by IAV Infection

BALB/c mice were treated with intranasal administration of IL-7-mFc, and after 14 days, infected with 3 LD₅₀ of H5N2. H & E staining and total inflammation index of lung sections at 50× magnification, and total protein concentration in BALF were analyzed at day 7 after infection.

As shown in FIGS. 9a and 9b , the histopathological parameters for airway inflammation after 7 days post-infection was significantly reduced in the lungs of mice given IL-7-mFc pretreatment compared to PBS-treated mice (FIG. 9a ). The number of pulmonary neutrophils (Gr-1^(high)Ly6c^(low)CD11b⁺) was sharply decreased in IL-7-mFc-treated mice at days 3 and 7 after infection, and the numbers of monocytes (CD11b⁺CD11c⁻Ly6c⁺) and inflammatory macrophages (CD11b⁺CD11c⁺MHCII⁺Ly6c⁺F4/80⁺) were also decreased at day 3 after infection in IL-7-mFc-treated mice (FIG. 9b ). 

The invention claimed is:
 1. A method for preventing or treating a disease caused by influenza virus in a subject in need thereof, comprising administering to the subject an effective amount of a composition comprising an interleukin-7 (IL-7) fusion protein and a pharmaceutically acceptable carrier, wherein the administration is an intranasal administration; and wherein the IL-7 fusion protein is represented by the formula: N′-Fc-A-IL-7-C′ or N′-A-IL-7-Fc-C′ wherein N′ is the N-terminus of the fusion protein; C′ is the C-terminus of the fusion protein; A is selected from the group consisting of glycine, methionine-methionine, glycine-glycine, methionine-glycine, glycine-methionine, methionine-methionine-methionine, methionine-methionine-glycine, methionine-glycine-methionine, glycine-methionine- methionine, methionine-glycine-glycine, glycine-methionine-glycine, glycine-glycine- methionine, and glycine-glycine-glycine; IL-7 is an interleukin 7 comprising the amino acid sequence of SEQ ID NO: 1, 2, 3, 4, 5, or 6; and Fc comprises the amino acid sequence of SEQ ID NO: 9, 10, 11, 12, 13, or
 14. 2. The method of claim 1, wherein the A-IL-7 of the formula: N′-Fc-A-IL-7-C′ or N′-A-IL-7-Fc-C′ comprises the amino acid sequence of SEQ ID NO: 15, 16, 17, 18, 19 or
 20. 3. The method of claim 1, wherein the IL-7 is fused directly to the N-terminus or C-terminus of the immunoglobulin Fc region or fused via a linker.
 4. The method of claim 1, wherein in the formula N′-A-IL-7-Fc-C′, the A-IL-7 is linked directly to the N-terminus of the immunoglobulin Fc region or via a linker.
 5. The method of claim 1, wherein the influenza virus is H7N9, H5N1, H5N2, H3N2 or H1N1.
 6. A method of reducing an expression of influenza virus mRNA in a subject in need thereof comprising administering to the subject an effective amount of a composition comprising an interleukin-7 (IL-7) fusion protein, and a pharmaceutically acceptable carrier, wherein the administration is an intranasal administration; and wherein the IL-7 fusion protein is represented by the formula: N′-Fc-A-IL-7-C′ or N′-A-IL-7-Fc-C′ wherein N′ is the N-terminus of the fusion protein; C′ is the C-terminus of the fusion protein; A is selected from the group consisting of glycine, methionine-methionine, glycine-glycine, methionine-glycine, glycine-methionine, methionine-methionine-methionine, methionine-methionine-glycine, methionine-glycine-methionine, glycine-methionine-methionine, methionine-glycine-glycine, glycine-methionine-glycine, glycine-glycine-methionine, and glycine-glycine-glycine; IL-7 is an interleukin 7 comprising the amino acid sequence of SEQ ID NO: 1, 2, 3, 4, 5 or 6; and Fc comprises the amino acid sequence of SEQ ID NO: 9, 10, 11, 12, 13, or
 14. 7. A method of protecting a subject from influenza virus infection comprising administering to the subject a composition comprising an interleukin-7 (IL-7) fusion protein, and a pharmaceutically acceptable carrier, wherein the administering is carried out by an intranasal route; and wherein the IL-7 fusion protein is represented by the formula: N′-Fc-A-IL-7-C′ or N′-A-IL-7-Fc-C′ wherein N′ is the N-terminus of the fusion protein; C′ is the C-terminus of the fusion protein; A is selected from the group consisting of glycine, methionine-methionine, glycine-glycine, methionine-glycine, glycine-methionine, methionine-methionine-methionine, methionine-methionine-glycine, methionine-glycine-methionine, glycine-methionine-methionine, methionine-glycine-glycine, glycine-methionine-glycine, glycine-glycine-methionine, and glycine-glycine-glycine; IL-7 is an interleukin 7 comprising the amino acid sequence of SEQ ID NO: 1, 2, 3, 4, 5 or 6; and Fc comprises the amino acid sequence of SEQ ID NO: 9, 10, 11, 12, 13, or
 14. 8. A method for preventing or treating a disease caused by influenza virus in a subject in need thereof, comprising administering to the subject an effective amount of a composition comprising an interleukin-7 (IL-7) fusion protein and a pharmaceutically acceptable carrier via an intranasal administration, wherein the IL-7 fusion protein comprises the amino acid sequence of SEQ ID NO: 22, 23, 24, or
 25. 